University of Maryland researchers aiming to combat rising global temperatures have developed a new “cooling glass” that can turn down the heat indoors without electricity by drawing on the cold depths of space.

The new technology, a microporous glass coating described in a paper published Thursday in the journal Science, can lower the temperature of the material beneath it by 3.5 degrees Celsius at noon, and has the potential to reduce a mid-rise apartment building’s yearly carbon emissions by 10%, according to the research team led by Distinguished University Professor Liangbing Hu in the Department of Materials Science and Engineering.

The coating works in two ways: First, it reflects up to 99% of solar radiation to stop buildings from absorbing heat. More intriguingly, it emits heat in the form of longwave infrared radiation into the icy universe, where the temperature is generally around -270 degrees Celsius, or just a few degrees above absolute zero.

In a phenomenon known as “radiative cooling,” space effectively acts as a heat sink for the buildings; they take advantage of the new cooling glass design along with the so-called atmospheric transparency window—a part of the electromagnetic spectrum that passes through the atmosphere without boosting its temperature—to dump large amounts of heat into the infinite cold sky beyond. (The same phenomenon allows the earth to cool itself, particularly on clear nights, although with much less intense emissions than those from the new glass developed at UMD.)

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